Method of making light sensitive polymerizable compositions

ABSTRACT

A light-sensitive composition comprising novel arylglyoxyalkyl acrylates that exhibits useful light sensitivity. The basic structure of the new compositions, which may also themselves be polymerized are as follows: ##STR1## wherein Ar represents an aromatic structure selected from the group consisting of benzene, naphthalene and substituted products of each, R 1  represents an alkyl group having from one to ten carbon atoms, R 2  represents a grouping selected from the group consisting of hydrogen, or a lower alkyl group having from one to five carbon atoms and R 3  represents an alkenyl group having from one to ten carbon atoms and singular unsaturation. The light-sensitive compositions may themselves be utilized in photochemistry as photopolymers, they may be combined with suitable solvents and additives or polymerized with suitable backbone polymers to provide substances which can be used as light-sensitive coatings. These coatings may be placed on substrates and in one instance as presensitized lithographic plates.

This is a division of application, Ser. No. 363,018, filed 5/23/73, nowU.S. Pat. No. 3,930,868.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of art to which this invention pertains is light-sensitivecompositions and products made therefrom. In particular, the pertinentprior art can be found in those areas dealing with photo-sensitivecompositions or photo-sensitive substances made therefrom. Printing orimaging plates in general or presensitized lithographic plate art orphoto-sensitive polymeric art will be the most relevant.

2. Description of the Prior Art

Photo-sensitive compounds which are polymeric substances are well knownin the art. In particular, these substances can be used in a widevariety of photochemical processes. For example, they can be placed onresilient surfaces and be used for many types of printing plates andparticularly for lithography or offset printing, or they can be used forthe production of printed circuit boards by chemical milling andetching. The claimed compositions are particularly suitable for use asphotopolymers in light-sensitive coatings for lithographic plates or inother systems such as relief plates, general resists, silk screens, etc.They may also be used in printing inks or other light-sensitivecoatings.

In a commercial sense, and in particular in the production oflithographic plates, a light-sensitive coating is generally placed on abacking member which in many instances is a metallic substance. Anegative or other means to control light exposure to the plate isutilized to selectively cause the areas of the plate struck by a lightto become differentially soluble with respect to a solvent, which issubsequently used to flush the non-exposed substance from the backingplate. The image area or the area which has been subjected to lightbecomes receptive to inks while the non-image area or the area which hasnot been contacted with light, and which typically has been washed awayby a suitable solvent, is not receptive to ink. Therefore, the printingof an object can be accomplished by contacting the developed plate witha particular ink which adheres only to the areas of the plate which havebeen struck by light. Thereafter, the plate can be contacted with atransfer roll or directly with paper for transfer of ink from the imageareas.

Early in the prior art such light-sensitive plates were prepared forimmediate use. Because of the nature of the light-sensitive materialsutilized their storage or shelf like was substantially reduced whensubjected to the atmosphere or to humidity or to extraneous light inrelatively small quantities. An improvement over these substances is nowknown. Many of the presensitized lithographic plates utilized inindustry are made of such light-sensitive materials that they arevirtually indestructible when contacted with air or moisture, but whencontacted with certain wavelengths of the electromagnetic spectrumbecome substantially instantaneously reacted, thereby rendering a lightsensitized product.

The present invention is suitable for use in presensitized lithographicplates or in other areas of photopolymeric chemistry wherein a materialwhich when contacted with certain wavelengths of the electromagneticspectrum becomes polymerized or insolublized with respect to a solventand which thereafter can be utilized, for instance in the lithographicplate field, as image-receptive areas. In another instance, theparticular photosensitive compounds claimed herein, can be utilized inconjunction with a certain polymeric system so that when contacted witha certain spectrum of electromagnetic radiation the polymeric system canbe degraded, thereby rendering a material which can decompose uponcontact with light. In particular, the latter application has been ofinterest in the packaging industry to help reduce littering problems.For instance, such a polymeric system might upon exposure to sunlightbecome very brittle through a photoreaction enabling it to be moreeasily weathered by the elements. The use of our particular componentsin such a polymeric system can allow the container, which when subjectedto various quantities or various spectrums of electromagnetic radiationcan decompose in a predictable manner, thereby reducing the threat ofpollution from containers indiscriminately disposed of.

BRIEF SUMMARY OF THE INVENTION

Our invention can be summarized as a light-sensitive and polymerizablecomposition comprising an arylglyoxyalkyl acrylate and having thefollowing general structure: ##STR2##

Additionally, our invention can be summarized as a light-sensitivecomposition comprising repeating arylglyoxyalkyl acrylate substituentunits attached to a backbone polymer which substituent units have thefollowing general structure as described below: ##STR3##

Additionally, our invention can be summarized as a lithographic plateincluding a support member comprising any resilient material and a filmformed from a light-sensitive composition said composition comprisingarylglyoxyalkyl acrylate units as described above.

In a broad embodiment, our invention relates to a light-sensitive andpolymerizable composition comprising an arylglyoxyalkyl acrylate havingthe following general structure: ##STR4## wherein X represents anaromatic selected from the group consisting of benzene, naphthalene andsubstituted products of each or a heterocyclic such as thiophene andpyrrole, R₁ represents an alkyl group having from one to ten carbonatoms, R₂ represents a grouping selected from the group consisting ofhydrogen, or a lower alkyl group having from one to five carbon atomsand R₃ represents an alkenyl group having singular unsaturation and fromone to ten carbon atoms.

Another embodiment of our invention resides in a light-sensitivecomposition comprising repeating arylglyoxyalkyl acrylate substituentunits attached to a backbone polymer which substituent units leave thefollowing general structure: ##STR5## wherein Ar, R₁ and R₂ are as aboveand R₃ is alkyl group having from one to ten carbon atoms.

Another broad embodiment of our invention relates to a lithographicplate including a support member and a film formed from alight-sensitive composition, said composition comprising repeatingarylglyoxyalkyl acrylate units which units have the following generalstructure: ##STR6## wherein Ar represents an aromatic selected from thegroup consisting of benzene, naphthalene, and substituted products ofeach or a heterocyclic, R₁ represents an alkyl group having from one toten carbon atoms, R₂ represents a grouping selected from the groupconsisting of hydrogen or an alkyl group having from one to five carbonatoms and R₃ is an alkyl group having from one to ten carbon atoms.

Still another embodiment of our invention is a light-sensitivecomposition comprising a backbone polymer which has appended from it thefollowing grouping: ##STR7## wherein Ar and R₁ are as described above.

DETAILED DESCRIPTION OF THE INVENTION

The novel compositions of this invention can generally be characterizedas arylglyoxyalkyl acrylates which may be present as individualmolecules by themselves or with a suitable binding substance such as apolymeric backbone. When in an unpolymerized state they may berepresented by the following formula: ##STR8## When in a polymerizedstate prior to light exposure they may be attached to themselves or to abackbone polymeric substance. In the polymerized state and prior toexposure to light they may be represented as follows: ##STR9##

In the above formulas, the aryl component referred to in the generalformulas as Ar can be any material of aromatic qualities such asbenzene, toluene, xylenes, singular or multiple alkyl or arylsubstituted aromatics as well as aryl or alkyl singular or multiplesubstituted aromatics which may also contain nitrogen, sulfur, hydroxy,carboxylic or carbonyl groups or compounds containing those materialsfor example, but not necessarily limited to the above listing. Otheraromatics such as heterocyclics such as pyrroles, thiophene,phenanthroline, etc., may be used. A particular substitution such asalkoxy on a singular aromatic enhances the light sensitive properties ofthe above structure. The aromatic grouping may also include suchstructures as polynuclear aromatic groupings, phenanthrenes, indanes,indenes, the bi-phenols, pyrenes, and other similar type multiple ringedaromatic behaving substances. It is preferred, however, that thearomatic component of the above formulas or any substitution thereon beselected so that it will not adversely or substantially reduce thephotosensitive nature the light-sensitive portion of the composition. Itis also preferred to choose aromatic structures and substitutionsthereon that will not polymerize prior to light exposure so as tomaintain the aromatic portion together with the light sensitive portionof the compound as pendent entities when the composition is attached toa backbone polymer.

R₁ as defined in the above structure is preferably a simple alkylgrouping having from about one to about 10 carbon atoms which themselvesmay be substituted with alkyl, aromatic, alkenyl, halogen or other typesubstituents such as hydroxy, carbonyl, sulfur, nitrogen, or othersubstitutable groups. It is preferable, however, that the R₁ alkyl groupbe selected so that it does not adversely affect the light sensitive orthe polymerizable portions of the above compound. R₁ may also containamino groupings within the chain itself.

R₂ in the above formula can generally be selected from those groupsdefined as above or the R₁ grouping. Specifically, hydrogen or a loweralkyl grouping is preferred as the R₂ substituent. Specifically, thissubstituent should contain materials which will not adversely affect thevinyl bond in the R₃ portion of the above formula.

R₃ in the structure immediately above is preferably alkyl having fromone to 10 carbon atoms. However, when representing R₃ in the structuralformula for the unpolymerized composition, R₃ is alkenyl of from one to10 carbon atoms and preferably with singular unsaturation. R₃ may besubstituted with alkyl, aryl, alkenyl or other substitution components.Additionally, amino, carbonyl, hydroxy or other substitutable groupingsmay be added, It is required that any substitution on the R₃ group notprevent it from entering into polymerizing reactions.

The light-sensitive portion of the above compounds is represented by thefollowing arylglyoxyalkyl segment of the claimed composition: ##STR10##when exposed to actinic light this segment becomes activated causingpolymerization at or near the carbonyl groupings. The exact mechanisimis not known but it is observed that exposure to electromagneticradiation of certain wavelengths will cause the claimed compound to beinsoluble to certain solvents. In some instances the alkenyl group mayalso participate in photolysis. The light-sensitive portion may initiatethe polymerizable portion for cross linking.

The portion of the claimed material which is utilized to polymerize thecompound to itself or to another monomer on a backbone polymer isrepresented by the vinyl containing alkyl acrylate segment as shownbelow: ##STR11## wherein R₃ is one carbon atom long. Preferably, priorto contact with light, the claimed compound is polymerized with amonomer or a backbone polymer through this vinyl bond to form a filmwhich can be used in conjunction with a suitable backing plate to form alithographic plate in one instance.

The arylglyoxyalkyl acrylate components either represented as anunpolymerized molecule or when present in the polymerized state may beused in conjunction with other compounds. In particular, when thearylglyoxyalkyl acrylate is utilized as a substituent structure of apolymerized nature, it may be hung on a backbone polymeric substance bya grafting procedure. Additionally, the arylglyoxyalkyl acrylates of ourinvention when utilized as polymerized substances may themselves besubstituted with monomers similar or identical to the arylglyoxyalkylacrylates to present a photosensitive polymeric substance. It iscontemplated that when the arylglyoxyalkyl acrylates are co-polymerized,that identical arylglyoxyalkyl acrylates may be polymerized in a chainfashion to produce a molecular weight polymer having a desired property.Additionally, arylglyoxyalkyl acrylates which have differentsubstitutions on the aryl, alkyl or alkenyl groupings may becopolymerized, grafted onto a backbone or combined with a monomer havinga different structure.

The arylglyoxyalkyl acrylates as described in the claims and in theabove formulas may be polymerized with backbone polymeric substances.These backbone structures preferably are organic and may be selectedfrom materials including natural and synthetic resins. Typical backbonematerials which contain hydroxyl substitutable components include forexample, polyvinyl alcohol, partially hydrolyzed polyvinyl esters suchas polyvinyl alcohol-co-vinyl acetate, polyvinyl alcohol co-vinylbenzoate, polyvinyl alcohol co-vinyl acetate co-vinyl benzoate,partially hydrolyzed polyvinyl acetals such as partially hydrolyzedpolyvinyl butyral, partially hydrolyzed polyvinyl benzal, partially,hydrolyzed polyvinyl cinnamal as well as mixtures of such partiallyhydrolyzed acetals, polyethers such as epoxy and phenoxy polymers, etc.Additionally, the condensation product of bisphenol such asdiphenylolpropane with epichlorhydrin, naturally occuring materials suchas cellulose, starch, guar alginic acid and their partially esterifiedor etherified derivatives for example, ethyl cellulose, hydroxyethylcellulose, hydroxylpropyl cellulose, polyesters of polyhydroxyintermediates such as glycerol and sorbitol which have hydroxyl groupsremaining after incorporation into the polymeric chain. Additionally,backbone polymers containing reactive amino groups for example,polyvinyl amines, polyaminostyrenes, polyvinyl anthranilates, etc., andpolymers containing reactive anhydride groups, for example, copolymersof maleic anhydride with ethylene or styrene. Other backbone structuredmaterials may be utilized which would readily react with the vinylgrouping on the claimed light sensitive compound.

Vinyl groupings may also be used to form a copolymer product with thearylglyoxyalkyl acrylate. Such vinyls can include the ubiquitous styreneor methyl vinyl ether, methylmethacrylate, acrylamide, diacetoneacrylamide, vinyl choride, hydroxy-ethyl acrylate, vinyl pyrrolidone,acrylonitrile derivatives thereof, etc. Other examples of suitablebackbone polymers include: the aliphatics such as methylene, ethyleneand propylene; the aromatics such as phenylene, biphenylene, naphthaleneand anthracene; the substituted aromatics such as toluene,ethylphenylene, aminophenylene, alkoxyphenylenes (e.g.methoxyphenylene), cyanophenylene, hydroxyphenylene, the halophenylenes(e.g. chlorophenylene,) ethylnaphthalene, carboxyphenylene, difunctionalderivatives of the phthalates and substituted phthalates such as thehydroxy alkylphthalate compounds (e.g. hydroxyetylphthalate) andacyloxyphenylenes (e.g. acetoxyphenylene); heterocyclics such asdifunctional derivatives of cyclopentane, cyclohexane, thiophene andpyrrole; the organometallics such as difunctional derivatives of themetallocenes such as ferrocene; polymeric materials such aspolyalkylenes (e.g. polyethylene, polypropylene and polybutylene);polyesters such as polyethyleneterephthalate and polyethyleneadipate;polyurethanes such as the toluene diisocyanate polyol urethanes;polyamides such as polyhexamethyleneadipamide; copolymers such asvinylidene chloride/vinyl chloride copolymers; the polysiloxanes; thepolyalkyleneoxides (e.g. polyethylene oxide, polypropylene oxide,polybutylene oxide, polytetramethylene ether and polyepichlorohydrin);the polyalkylene imines such as polyethyleneimine andpolypropyleneimine; substituted polyakylenes such aspolyvinylpyrrolidone; and phenolic derivatives such as novolac, resoleand polyphenylene oxide.

As previously noted, the photoreactive compositions of the presentinvention can be used alone or in conjunction with other materials toprovide photoreactive compositions suitable in a wide variety ofphotomechanical and photochemical processes. For example, these novelcompositions exhibit advantageous utility as photoinitiators with bothsaturated and unsaturated resins including resins which are notphotosensitive in themselves. In particular, durable insolublephotoreaction products can be formed through the conjoint use of thephotoreactive compositions of the present invention as photoinitiatorswith a wide variety of resins, including: the acrylic polymers andacrylic ester resins such as polymethylmethacrylate,polyethylmethacrylate, and copolymers of methyl and butyl methacrylate(e.g. "Elvacite"); polyurethane resins such as those formed fromdiisocyanates such as, for example, toluene diisocyanate, low molecularweight polyesters and low molecular weight polyethylene glycols (e.g."Estante" polyurethane resins); blocked urethane resins such as, forexample, phenol blocked polyurethane resins (e.g. "Tranco 3A" blockedurethane resins); alkyl celluloses such as ethyl cellulose (e.g."Hercules K-type" ethyl cellulose); epoxy resins (e.g. "Epon 1004" whichis the condensation product formed from bisphenol A andepichlorohydrin); phenoxy resins (e.g. "Bakelite PKHH" phenoxy resin);vinyl acetate/vinyl chloride copolymers (e.g. "Bakelite VYHH" an 86%vinyl chloride, 14% vinyl acetate copolymer medium molecular weightresin); vinyl modified polyethylene such as ethylene/vinyl acetatecopolymer containing 2 to 50% vinyl acetate ("Ultrathene" ethylene/vinylacetate copolymer); partially (5 to 80%) hydrolyzed vinyl acetate);phenolic resins (e.g. "Plenco 1000" novolac resin); acrylamide andmodified acrylamide polymers such as diacetone acrylamide homopolymer,N-methylol acrylamide, N-alkoxymethyl acrylamide and partiallyhydrolyzed acrylamide; water-soluble cellulose derivatives such as thealkoxylated celluloses and hydroxypropyl cellulose (e.g. "Klucel"hydroxypropyl cellulose); and water-soluble polyether resins such as thepolyalkylene oxide (e.g. "Polyox WSRN-80" polyethylene oxide).

The exact quantity of the arylglyoxyalkyl acrylate component which maybe used as a photosensitive material when combined with other materialssuch as backbone polymers, other or similar monomers, or solvents, canvary depending upon the degree of photosensitivity desired and theparticular solvent or other polymer utilized. Specifically, when thearylglyoxyalkyl acrylates of our invention are utilized with a solventand placed on a suitable backing plate, the solvent may vary anywherefrom about 99 weight percent to about 40 weight percent or lower byweight of the total mixture of solvent and light-sensitive compound.After deposition on the plate, some or most of the solvent can beevaporated leaving a thin film of the arylgyloyxalkyl acrylate whichpreferably are not polymerized. Upon exposure to an actinic light thisfilm can become insolublized with respect to certain solvents which areused to wash the unpolymerized soluble material from the plate. In someinstances, the arylglyoxyalkyl acrylates can be copolymerized with asimilar monomer and mixed with a solvent and applied as described above.In other instances, the arylglyoxyalkyl acrylates can be polymerizedwith another and substantially different structure monomer and thenmixed with a solvent and placed on a suitable backing member, again, asdescribed above.

In other instances in which the arylglyoxyalkyl acrylate compounds arehung on a backbone chain, their concentration should be controlled toyield optimum results. Depending upon the molecular weight of thebackbone chain and the molecular weight of the arylglyoxyalkyl acrylatependent molecule, the light-sensitive composition should vary anywherefrom about less than one up to about 60 weight percent of the totalpolymeric mixture. In some instances, the percentage of thelight-sensitive compound can vary above or below the above cited rangessince those ranges are disclosed as a general teaching.

The light sensitive segment (arylglyoxyalkyl) of the arylglyoxyalkylacrylate may itself be substituted in a pendent manner onto a backbonepolymer through the alkyl grouping. In such instances the pendent groupwould have a structure as follows: ##STR12## wherein Ar is an aryl or aheterocyclic aromatic and R₁ is an alkyl group having from one to 10carbon atoms.

Also, the light-sensitive compound which is polymerized with a monomeror a backbone polymer may be mixed with suitable solvents in varyingconcentrations and applied to a suitable backing plate. The quantity ofsolvent and polymer can be varied to meet performance standards asmentioned previously. Suitable solvents which can be utilized to lay theclaimed composition upon a suitable backing plate are known in the artand are not critical in adequately describing our invention. Typicalsolvents which can be utilized, include methylethyl ketone andrelatively inert aromatic hydrocarbons.

The light-sensitive composition when placed upon a suitable backingplate with a solvent or grafted onto a backbone polymer or copolymerizedwith itself, a similarly structured arylglyoxyalkyl acrylate or, asimilar monomer is sensitive to actinic light and especially toultraviolet radiation having wavelengths up to about 4,000 angstromunits. With suitable sensitizers, which are well known in the art, therange of sensitivity of the particular component to light can beextended. Specific sensitizers are known in the art and their detaileddescription is not necessary in order to appreciate the claimedinvention. Other additives such as dyes, plasticizers, etc., may be usedas needed and commonly known in photosensitive plate technology.

Preparation of the arylglyoxyalkyl acrylate materials can involve asynthesis of phenylglyoxylic acid with anyone of a number of acryliccompounds having hydroxy groupings.

In particular, preparation of the claimed compounds specifically caninclude the condensation reaction of phenylglyoxylic acid and2-hydroxyethyl methacrylate. These two materials are reacted, water isdriven off and the resultant phenylglyoxyethyl methacrylate is produced.In producing the hydroxy substituted acrylate, an unsaturated acid canbe reacted with a cyclic ether, preferably of low molecular weight, toform the resulting hydroxy substituted acrylate. The substitutedacrylate can then be reacted with a phenylglyoxylic acid to produce aproduct claimed herein.

To produce the hydroxy substituted acrylate, ethylene oxide can becombined with methacrylic acid to form 2-hydroxyethyl methacrylate. Theresultant methacrylate can then be reacted with phenyl glyoxylic acid toform a particular arylglyoxyalkyl acrylate claimed by us.

Other unsaturated acids similar to acrylic or methacrylic acid may beutilized to be combined with certain cyclic ethers to provide thehydroxy substituted acrylate which when combined with thephenylglyoxylic acid can produce the compound claimed by us. Other suchunsaturated acids include crotonic acid, preferably other relativelylinear unsaturated acids in which the vinyl bond appears once in thealkenyl chain connected to the carboxylic group. Other cyclic ethers maybe used in the synthesis of the hydroxy substituted acrylate. Examplesinclude higher homologs of ethylene oxide.

By varying the particular unsaturated acids and cyclic ethers used toproduce the hydroxy substituted acrylate, the R₁ and R₂ groupings of theclaimed compound or polymer units can be varied to encompass the scopeof the claimed subject matter.

A light-sensitive polymer composition according to the claims attachedmay also be prepared by an emulsion polymerization process. For example,the arylglyoxyethyl acrylate may be homo or copolymerized, using asuitable emulsifying surfactant and an initiator. Further, the emulsionparticles may contain additives such as dyes, pigments, sensitizers,plasticizers, etc. Alternatively, the aqueous phase may contain watersoluble polymers and other additive materials. The advantages oflight-sensitive polymers produced by the emulsion polymerization stepare listed below:

(1) High molecular weights can be produced at low coating viscositieswhich should result in a fewer photo-induced cross-links being necessaryfor photo-insolubilizations;

(2) Water may be used as the dispersing medium which could, in manyinstances, eliminate the solvent hazards associated with non-aqueoussolvents, such as toluene or xylene;

(3) Inherent stability as compared to prior art nonemulsionpolymerization processes;

(4) Simplicity of use as compared to other systems;

(5) Water development may be used in some cases reducing the need forsolvent washes using expensive or dangerous solvents;

(6) Micro-mixes with other emulsion polymers may be made easily andquickly to achieve a wide range of physical and photosensitiveproperties;

(7) Thicker coatings can be applied easily if greater relief is desired.

Emulsion polymer latex particles can range anywhere from 100 angstromsto micron sizes in diameter. Suitable techniques for the preparation ofemulsion polymers may be found in the prior art. In particular,Preparative Methods of Polymer Chemistry, InterScience Publishers, NewYork 1968, Second Edition, By W. R. Sorenson and T. R. Campbell,presents adequate teachings for such processing techniques.

The following examples are presented to specifically illustrate oneembodiment of our invention and are not to be read so as to unduly limitthe scope of the appended claims

EXAMPLE I Synthesis of Phenylglyoxyethyl Methacrylate

50 grams (0.333 moles) of phenylglyoxylic acid (Aldrich No. B1305-5 and,Matheson, Coleman, and Bell No. PX 765,P9432), 52.3 grams (0.40 moles)2-hydroxyethyl methacrylate (Eastman P8366) which containedapproximately 84% hydroxyethyl methacrylate according to gaschromatographic measurements, and 700 milliliters of benzene werecharged into a one liter one neck flask. A DeanStark trap and watercondenser were fitted to the flask. The reaction mixture was thenrefluxed 25 hours and 24 minutes after which 4.5 milliliters of waterwas collected. The cooled light green solution recovered was washed fivetimes with 250 milliliters of a 10 percent by weight NaHCO₃ solution.The basic material was dried over Na₂ SO₄ and stripped on a flashevaporator at less than 40° C to constant weight. 53.2 grams of lightyellow liquid was recovered. 45.3 grams of the light yellow liquid wasplaced in a separatory funnel to which 500 milliliters of carbontetrachloride was added and washed ten times with 250 milliliters of tapwater. The washed material was dried over Na₂ SO₄. The material was thenfiltered and stripped on a flashed evaporator at less than 45° C. Thefiltered material was a yellow liquid and weighed 15.8 grams. Uponexamination of this material by infra-red spectrographic analysis it wasdetermined that the synthesis of phenylglyoxyethyl methacrylate had beenperformed.

EXAMPLE II Light Sensitivity Testing

A solution of three grams of the end product of Example I plus 97 gramsof a 50--50% mixture of methylethyl ketone and acetone was prepared. Thesolution was coated on an aluminum brush grained plate two times. Theplate was exposed ten minutes to pulsed xenon ligh through a step wedge.The exposed plate was then developed with a sodium silicate solution.Small print on the step wedge was clear. Under the same conditions,starting (reacted) materials utilized in Example I (phenylglyoxylicacid) gave poor results.

EXAMPLE III Light Sensitivity with a Sensitizer

A solution was prepared containing 0.3 grams of benzoin, 2.7 grams ofphenylglyoxyethyl methacrylate from Example I and 97 grams of 50--50mixture of methylethyl ketone and acetone. The solution was mixed andcoated on an aluminum brush grained plate by dipping the plate in thesolution. The plate was exposed 10 minutes to pulsed xenon light througha step wedge. The plate was developed with a sodium silicate solution.Numbers 15 through 21 on the step wedge came out sharp and clear afterdeveloping.

EXAMPLE IV Preparation of a Relief Plate

A three square inch brushed grained aluminum plate was coated with theproduct of Example I (phenylglyoxyethyl methacrylate). The monomer wasfirst wiped on with lithograph pad material and then put on with adropper. Although a uniformly thick coating was not insured with thisprocedure it was only desired to place a workable thickness of thephenylglyoxyethyl methacrylate upon the aluminum plate to test its useas a relief plate. An aluminum sheet into which a design had been cutwas placed over the coated plate and was somewhat raised from the plateto prevent contact therewith. The unit was exposed to ultraviolet lightfor two hours. The exposed plate was washed with a sodium silicatesolution and then with methylethyl ketone to remove unexposed, solubleareas. An adherent plastic coating was obtained in the exposed areas.The color of the coating was a light greenish-yellow. There apparentlywas not much if any discoloration of the polymerized material from thestarting monomer.

EXAMPLE V Relief Printing Plate Preparation

A three by three inch brushed grained aluminum plate was coated byrepeated application and evaporation of a clear solution comprising 2grams of the phenylglyoxyethyl methacrylate product of Example I, 0.4grams of xanthene-9-one, and 25 grams of methylethyl ketone. The platewas exposed and developed as described in Example IV. The color of theexposed and hardened material was light green and light green-yellow.Again, there was not much apparent discoloration of the exposed monomer.A micrometer was used to measure the thickness of the polymer coating.The coating was found to be approximately 0.01 inches thick.

We claim:
 1. A method of forming a light sensitive and polymerizablecomposition which comprises an effective amount of a polymer thatincludes as a recurring structure: ##STR13## wherein Ar represents anaromatic structure selected from the group consisting of benzene,naphthalene and substituted products of each, R₁ represents an alkylenegroup having from one to ten carbon atoms, R₂ represents a groupingselected from the group consisting of hydrogen, or a lower alkyl grouphaving from one to five carbon atoms, and R₃ represents an alkylenegroup having from one to ten carbon atoms; said method including thesteps of charging an arylglyoxyalkyl acrylate together with anemulsifying surfactant and an initiator into a reactor, saidarylglyoxyalkyl acrylate having the following general structure:##STR14## wherein Ar, R₁ and R₂ are as defined above and R₄ representsan alkenyl group having from one to ten carbon atoms, forming saidpolymer by emulsion polymerization, and thereafter recovering saidpolymer.
 2. The method of claim 1 wherein Ar is benzene.
 3. The methodof claim 1 wherein R₁ has two carbon atoms
 4. The method of claim 1wherein R₂ has one carbon atom.
 5. The method of claim 1 wherein Ar isbenzene, R₁ has two carbon atoms and R₂ has one carbon atom.
 6. Themethod of claim 1 wherein said polymer is formed by polymerization ofsaid arylglyoxyalkyl acrylate together with a material selected from thegroup consisting of vinyls and substituted vinyls.
 7. The method ofclaim 1 wherein R₃ has one carbon atom.